The present invention relates to a hot air blowing gun and, more particular, to a safety hot air blowing gun, which uses a protective ring to support the inner barrel inside the housing, enabling a part of induced currents of air to pass through open spaces around the inner barrel, so as to minimize transmission of heat from the inner barrel to the housing.
FIG. 1 shows a hot air blowing gun according to the prior art. This structure of hot air blowing gun comprises a housing A, an inner barrel and nozzle assembly C mounted inside the housing A and partially projecting out of the front side of the housing A, a high-impedance resistance type heating element (not shown) wound round the inside wall of the inner barrel and nozzle assembly C, and a fan motor assembly B mounted inside the housing A behind the inner barrel and nozzle assembly C and controlled to blow currents of air through the inner barrel and nozzle assembly C to the outside of the hot air blowing gun for application. This structure of hot air blowing gun is functional, however it has drawbacks. Because the nozzle of the inner barrel and nozzle assembly C projects out of the front side of the housing A, the user may touch the hot nozzle of the inner barrel and nozzle assembly C by an accident during the operation of the hot air blowing gun. During the operation of the hot air blowing gun, the temperature of the high-impedance resistance type heating element is as high as 500xcx9c600xc2x0 C., and the nozzle of the inner barrel and nozzle assembly C is continuously heated by hot air passing through. When touching the hot nozzle of the inner barrel and nozzle assembly C by an accident, the hand will be severely scalded with the hot nozzle. Further, the inner barrel and nozzle assembly C has a metal locating ring C disposed around the periphery and fastened to the inside wall of the housing A. Because the locating ring C is fastened to the inside wall of the housing A, it prohibits cold air from passing through the gap between the outside wall of the inner barrel and nozzle assembly C and the inside wall of the housing A to reduce the temperature of the body of the nozzle of the inner barrel and nozzle assembly C. After a certain length of time in operation, the temperature of the nozzle of the inner barrel and nozzle assembly C may become higher than the melting point of certain materials, for example, wood, plastics, paper, and etc. When touching materials of low melting point with the hot nozzle of the inner barrel and nozzle assembly C, the materials may be burned, causing a disaster.
The present invention has been accomplished to provide a safety hot air blowing gun, which eliminates the aforesaid drawbacks. It is the main object of the present invention to provide a hot air blowing gun, which minimizes the contact area between the inner barrel and the housing so as to reduce the transmission of heat from the inner barrel to the housing. It is another object of the present invention to provide a hot air blowing gun, which guides a part of the induced currents of air from the fan blade assembly through the space around the inner barrel, so as to reduce the contact temperature between the inner barrel and the housing. According to one aspect of the present invention, the safety hot air blowing gun comprises a housing, an inner barrel mounted inside the housing and holding a high-impedance resistance type heating element around the inside wall thereof, a nozzle tip fastened to the front side of the housing, a fan motor assembly mounted inside the housing behind the inner barrel and controlled to blow air through the inside of the inner barrel and the outside of the inner barrel within the housing, and a protective ring mounted within the housing to support the inner barrel, the protective ring having inside protruded portions abutted against the periphery of the inner barrel and defining a plurality of open spaces around the inner barrel for the passing of currents of air from the fan motor assembly to reduce the temperature of the peripheral wall of the inner barrel and to prevent the housing from deformation due to high temperature. According to another aspect of the present invention, a conical nozzle cap mounted on the front side of the housing around the nozzle tip and adapted to guide currents of air passing through the open spaces to the outside of the housing.